Autodesk 64006-051108-9001 User Guide - Page 199

Encode Tab 191 Chroma Format (MPEG-2 only) Sets the ratio of the luminance to chrominance (color) in Y'CbCr color space when encoding to MPEG-2. Y stands for luminance, Cb for blue minus luminance, and Cr for red minus luminance. With these three values it is possible to extract the value for the green channel. You can reduce the chroma in the encoding in Y'CbCr color space since the luminance and chrominance channels are separated. The chroma value is denoted in a ratio where the first value indicates luminance, and the following two values are used to calculate chrominance. • 4:2:0 - This chroma value yields a compression ratio of 2:1, with a quarter as much color value as luminance. 4:2:0 is recommended for content destined for internet playback. • 4:2:2 -This chroma value yields a compression ratio of 1.5:1, with half as much color value as luminance. 4:2:2 is recommended for content destined for playback on devices with high bit rate capacity. 4:2:2 is used in professional studio environments. The video minimum and maximum bit rate limits will vary depending on the MPEG-2 preset you choose, in combination with the chroma setting. After you select a preset and a chroma value, the values in the Bit Rate Group in the Encoder Setting dialog box will update. If you manually change these to a value outside of the limits, an explanation mark appears next to the field where a value is outside of the acceptable range. Output Field Dominance (MPEG-2 only) Select the field dominance (Top Field First, Bottom Field First) for the encoded video.